Did we watch the same trailer? He didn't do anything until he was standing (fully transformed) and that looked to me like something they fired at him, not something he used as a weapon. Just protected himself from.
The written ending of the leaked script? Placing faith in that is like betting red on wheel that is all black.
You guys need to give it a break. There have been how many iterations of Optimus Prime and the transformers in general over the years? Why can't this just be one more?